Direct panoramic optical imaging for closed surfaces.

Common methods for panoramic imaging of closed surfaces currently involve the use of motion or multiple cameras, combined with image processing algorithms to reconstruct a full-perspective image. These methods require image reconstruction and post-processing, which limits the accuracy of the imaging. In this study, we propose a silver-glass composite layered structure with subwavelength spacing to create an equivalent null medium in the optical band. By utilizing the null medium's directional projection property of optical waves, what we believe to be a novel lens, the direct panoramic optical imaging lens (DPOIL), is designed. Both 2D and 3D simulated results demonstrate that the proposed DPOIL can directly project a full-perspective optical pattern from a closed curved object surface onto a flat image plane. It achieves direct panoramic imaging over a wide spectral band from 544 to 734 nm for TM-polarized waves. The imaging process does not require image reconstruction or post-processing, thus enhancing the accuracy of panoramic imaging. The DPOIL proposed in this study has potential applications in biological surface imaging, panoramic detection, and other scenarios requiring panoramic direct imaging of closed surfaces within the optical band.